


Alpha Omega

by alesandrey



Category: Dr. STONE (Anime), Dr. STONE (Manga)
Genre: Alpha Ishigami Senkuu, Alpha/Beta/Omega Dynamics, Consensual Sex, Explicit Sexual Content, Fluff and Smut, Gen is a devil, Knotting, M/M, Mates, Omega Asagiri Gen, Sengen Week (Dr. STONE), Sengen soulmates, Smut, idk just sengen brainrot
Language: English
Status: Completed
Published: 2021-03-01
Updated: 2021-03-01
Packaged: 2021-03-13 01:15:46
Rating: Mature
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 2,871
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/29768502
Author URL: https://archiveofourown.org/users/alesandrey/pseuds/alesandrey
Summary: " Keep saying weird things and I'll seriously mess you up. "Gen's glare turned into a challenging look as he pulled senku closer their lips only millimeters apart." Try me, alpha. "And yep, Senku was now 10 billion percent sure that Gen, this lovely Omega underneath him is gonna be the death of him.
Relationships: Asagiri Gen & Ishigami Senkuu, Asagiri Gen/Ishigami Senkuu
Comments: 4
Kudos: 105





	Alpha Omega

**Author's Note:**

> Oh my god. I can't believe it ended like this haha. Idk my intention was some soft fluff but then again idk what happened that it lead to this. Anyways I hope you like this one guys. Thank you for reading love you all mwa.

Alpha Omega. 

  
Maybe it was just him being tired. 

  
Senku sighed as he massaged his temples. It has been what? More or so thousand of years after the petrification. He started his quest on reviving all petrified humans and rebuilding civilization from scratch together with Taiju and Yuzuriha which was now in Tsukasa's stronghold. Senku was left alone in the Ishigami village to find people that could help him in reaching his goal. Being the sole modern man in the village he had always thought it was pretty weird for everyone to smell....ordinary. Until he found out that everyone except from him doesn't have the secondary gender or the smell that comes along with it. 

  
Senku Ishigami is an alpha and he was certain no one else from the new generation has the same second gender as his. It actually was a bit of relief since his second gender had posed a bit of many problems like ruts and heat that may become something that slows him down on his science project so knowing that and confirming that everybody else smelled ordinary was a relief to Senku. Everything went smoothly. He has no problems controlling his animalistic instinct and somehow he had manage to supress his 'needs' due to his science herbs and medicines. It was all going fine until some certain mentalist came. 

It happened around the time when he had invented the noodles for the village. He was very busy working in and out of his lab just to chase the time he had left in making the kill-all sulfa drug. Senku had has his hands full. But he was an alpha, through and through. And having forcefully shutting off his alpha for 2 or 3 years had been amazing but everything has a limit. Senku's eyes immediately grew wide as he felt the wind caresses his back. He remembered the shivers that ran down his spine as he felt his alpha growl on to the flowery scent that wafted through his nose. He was quite alarmed on whom the scent belonged, he searched the village scanning every faces making sure he had not miss any faces...or did he?

  
\---

  
Maybe he was just tired. Senku thought. Maybe he was just tired that he's now smelling Gen's flowery scent as he made his way to his hut. As he walked closer the smell had sure gotten stronger and stronger enough that made Senku's alpha growled in eagerness and excitement. 

  
" Gen. " 

  
Senku breathed and pushed down the heavy lump on his throat. Right infront of him was the mentalist, back turned against Senku with his clothes almost off making the skin on his shoulders and nape visible through the alphas sight. 

  
Senku's alpha growled once again and he cursed the beast inside him because of that. The scent Gen produced didn't help either. The velvety smell of jasmine had completely dazed and made Senku's brain rot. He gritted his teeth as he watched painfully at the omega who was messily sprawled out on his bed. 

  
" G-gen. " He called again. 

  
He mentally pinched himself for stuttering. Gen didn't answer and instead only made a whining sound that senku didn't dare to even thought as a moan. Now isn't the time to let his animalistic instinct take control of him. Gen is an omega and he's currently in a dire situation that Senku wish he hadn't discovered. 

  
The omega lulled and turned too painfully slow for Senku's liking. Gen faced the scientist, face flushed and covered with sweat. The white of his hair sprawled messily across his face and forehead covering some of his features while the black was all over senku's sheets. His lashes batted slowly against the scientist gray orbs staring helplessly at Senku's crimson ones begging for the alpha to come and help. 

" S-senku-chan... " 

  
Gen's voice had never sounded so erotic. It was low and soft...and needy. Senku held on to the hut's side as he clutched his clothes tightly hoping he'd still get a hold of his sanity after witnessing such ravishing sight. 

  
That is when Senku noticed Gen wasn't wearing anything inside his yukata. He moved his trembling legs slightly making the fabric fall of exposing Gen's milky and sweaty thighs. Senku had held his breath as his eyes feasted at the sight million of thoughts running through his mind on how many great things could he do to that mouth watering thighs. He could see the slick slipping down on the inside of Gen's thighs and there is no way in hell could he stop himself now. 

He felt himself tighten below there and as he took a step further Senku had known he had made the biggest illogical mistake of his entire life. 

  
Senku wondered if was he really fast or was it the adrenaline and his animal instinct that made him move incredibly quick to where the omega in heat was lying. He moved the clothes that senku noticed was his, on to the side as he climbed up his bamboo bed staring at the omega. 

  
" S-senku-chan....." 

  
Ah, senku could swear he'd lost his sanity every time he'd hear the mentalist's voice. He had always has a nice voice and now that it was laced with pure lust and need it was far more angelic. 

  
Senku breathed. He placed his hands on the omega's cheek caressing the feverish skin. 

  
' mate. ' 

  
What? 

  
Gen closed his eyes as he tilted his head leaning against Senku's touch. Senku could've swore he'd heard the omega purr that made himself feel even more hot, like as if he had caught the omega's heat. He watched frozen as the omega batted his eyelashes puffing small hot breaths against his palm. 

  
Gen is a devil. 

  
The omega moved the hand that senku had used to cup his cheeks. With his gray orbs still locked on Senku's crimson ones Gen lifted his hand as he placed a wet and sloppy kiss on the inside of Senku's palm. He took the scientist's two fingers close to his mouth before slipping his tongue past his lips giving Senku's fingers kitten licks and then shoving it slowly inside his mouth giving it a soft suck as his eyes never left his. 

  
That's it. 

  
Senku growled at the omega. He pulled his hands as he lifted the other making him sit on his lap. Senku was right Gen wasn't really wearing anything and he was damn wet all over. Gen was basically naked except for the yukata that still hung on his waist. The omega whined at the sudden change of position but easily comforted himself as he leaned his forehead on senku's shoulders arms snaking around the younger's neck as he hugged and rubbed their bodies close. 

" Let's make this quick and get this over with omega. " 

The omega only whined and purred as he moved himself closer to senku. He hissed as he sloppily gnawed at Senku's clothes tugging and pulling it as he slowly rubbed his heat on senku's abdomen. 

  
Damn this omega. 

Senku caught Gen's hands and placed them again on his shoulders. He tilted Gen's chin as he kissed the side of his mouth purposely missing his lips as he felt that it was inappropriate and scared Gen wouldn't approved of it when he got his sanity back. Senku let his hands roam on Gens back he moved his palm caressing the mentalist spine tracing the bone down till his fingers reaches his lower back. His fingers danced along the curve that connects the small on Gen's back and his plump ass. Gen whined as he felt the alpha's hesitation and pushed himself more closer, his mouth kissing Senku's jaw and puffing small breath on his ear. 

  
" Hnng...alpha..touch.. " 

Senku obeyed. He let his hands fall down, palming the plump flesh of Gen's ass. Gen whined at the slight squeeze as he burried his face on the alpha's neck moving his hips a bit more aggressively making the alpha growl in response and earning the mentalist a light slap on his butt cheeks. 

  
Gen liked it. 

  
Senku felt his cheeks heat up even more. It was the omega's fault for rubbing his dick on his abdomen a bit aggressively that he couldn't stop himself from slapping the voluptuous ass. He felt the omega moan making his own cock twitch in excitement. 

  
Senku slipped his finger right above the crack on the omega's butt cheeks. He rubbed the wet hole teasing it as he plunge the tip of his middle finger and then pulling it back the moment it starts to close its wall around it. Gen clutched senku's back a bit harder, his nails digging at the alpha's skin as he mewled and moaned at the alpha's ministration. The alpha chuckled as he placed two fingers on Gen's entrace stretching the wet hole until it was big enough for both of his finger to enter. 

" A-ahh alpha..hurry.."

  
This mentalist.

Senku shook his head at the mentalist plead. So he becames impatient when he's in heat huh? Senku pushed two of his fingers inside. He tilted his head to the side as he kissed the mentalist's temple. Gen shook above him, moaning as he moved his hips, rocking it above senku's lap. Gen was covered in sweat, his eyes was close and his body was trembling. 

  
" Ahhh " Gen yelped as he felt the two fingers pushed deeper inside of him. He leaned back as he watched the alpha's face and stared at his crimson orbs that was covered with nothing but lust while he moved his ass syncing with the fingers movement inside his dripping hole. 

".....'s not enough.." 

  
" What? "

  
" Not enough. " 

  
Senku was taken a back as Gen raised his head. How could someone look so beautiful and erotic at the same time. Gen huffed as his eyes fogged up with tears. He bit his own lips as he scrambled on Senku's lap pushing himself a bit off and quickly pulling off the waistband of senku's pants. 

  
Senku's jaw hung open as he watched the omega undid his pants and successfully letting his throbbing cock out. The omega grinned playfully as his hands wrapped around the long and hard meat before running his thumb at the leaking slit. Senku growled and gripped Gen's wrist. Flicking them back as he pushed the omega down caging him between his arms. 

Senku had let his alpha take control over him. He licked his lips as he stared at the omega below him eyes full of lust and need to dominate and own the older below him. He lifted Gen's leg as he positioned himself right infront of Gen's leaking entrance stopping midway as he glances at the omega's pretty face. 

  
Gen was the definition of perfect. His puffed cheeks were tinted red as moans left his swollen lips. He raised his hands and cupped Senku's cheeks snaking his arm around his neck pulling him down to place a wet kiss on his cheeks. 

  
" Please.. alpha..." 

Senku didn't need to hear more. He pulled Gen's waist as he pushed his throbbing member inside the wet hole. Gen arched his back and lets out a load moan as soon as he felt the intrusion. Gen's finger dugged and scratched Senku's back as the latter pushed harder and deeper hitting the back of Gen's wall making the omega squirm underneath him. Senku gritted his teeth as he felt the older's wall clenched his meat, squeezing it with its velvety walls making him feel pleasure that he had never felt before. 

And when senku was certain that the omega had grown comfortable at his size, he started to move. If was slow at first afraid he would break the fragile looking omega under him but the latter didn't like it. The omega whined and wrapped his leg at senku's waist as he pulled him down kissing every part of his face. 

  
" Faster..please. " 

  
Damn it all. Senku was sure Gen is gonna be the death of him. He plunge forward burrying his meat deeper and then pulling himself out leaving only the tip before pushing it inside again hard and rough. Senku did the process repeatedly, constantly stopping as he catches his breath while wiping the omega's forehead ridding it of his sweat. His hands grip the omega's legs as he caresses his thighs and occasionally slapping the plump flesh everytime Gen clamps on him too hard. 

  
The omega was nothing but pretty. Senku almost came as he saw Gen's reaction after he hit his spot. The omega's hands fell to his side. His fingers curling over the sheet as his head was slightly thrown upward. His lips red and swollen, glistening under the moonlight as it was slightly a part letting out pleads and moan for Senku to go faster and harder. Gen open his gray eyes half lidded lashes framing its sharpness. His orbs were foggy and was covered with lust as he blinks tears of ecstasy every time senku hits the spot. Gen bit his lips as he smiled raising one hand to cup the alpha's cheeks. 

  
" ....haa...alpha.. pretty. " 

  
Senku swore he almost came as Gen whispered those three words. He could hear his heart thumping abnormally loud as he felt himself grew bigger inside of Gen. The omega arch his back as he felt his walls being stretched even more. He gasps as Senku continuously grew inside of him resizing his tight hole making it adjust to Senku's girth. Senku couldn't believe it. How could this happen? He unconsciously knotted the omega below him and aside from the fact that he was fucking surprised he was scared. Scared that Gen might not like it. 

He pressed his forehead on the crook of Gen's neck sighing a bit loudly for the omega's comfort as he stayed still on top of him. 

"Mn.. move senku-chan "

Senku scoff as he hugged Gen's waist locking the omega in a tight embrace but enough for Gen to breath comfortably. 

"...cant. "

  
" Why? "

  
" I... I accidentally knotted you. " 

Senku's heart wouldn't stop beating loudly. He was starting to get worried that Gen might hear it knowing how close he was embracing the older. His brows scrunched together as he felt the older tremble below him. 

" Fuck. Why are you laughing? "

  
Gen's giggle was like music to his ears. As corny as it may sound but the simple noise made Senku feel like he was lighter. He felt something bubbled low on his stomach as he felt his cheeks burning. He hugged the mentalist closer clicking his tongue. 

" I can't believe you knotted me. Are you in a rut? "

  
" I can't believe it either. It's because you keep on saying weird things while looking so pretty under me. "

As soon as Senku finished his sentence they both flushed against each other, them both embarrassed on what Senku had said. Gen bit his lips and moved his hands to wrap around Senku's waist. He exactly doesn't know how things led to this but one thing is for sure he wasn't regretting anything, in fact he was more than...glad that Senku was with him. That senku had did this to him. He exhaled a deep breath as he pressed a soft kiss on the younger's temple. 

" How long does your knot usually last? "

"....I-i dont know.. "

Gen was silent for a moment. 

  
" This..this is your first time? "

" Why the hell are you so shock I was just 17 when I was petrified plus im not interested in engaging on sex. Tsk. " 

  
Gen didn't answer. He felt something bubbled on his chest. A triumphant feeling knowing that he was the younger's first. 

  
" Guess we'll just have to wait until you shrink. Your size is messing my insides up senku-chan. " 

Senku groaned and glared at gen's neck. He pushed himself back up untying Gen's legs on his waist earning him a confused look from the omega. His crimson orbs locked gazes with Gen's gray ones as he smirked and thrusted forward. Gen yelped in surprise his hands automatically went to Senku's neck as he felt his girth inside him move. He glared back at the alpha, lips slightly open as he hitches his breath. 

" Keep saying weird things and I'll seriously mess you up. " 

Gen's glare turned into a challenging look as he pulled senku closer their lips only millimeters apart. 

" Try me, alpha. " 

  
And yep, Senku was now 10 billion percent sure that Gen this lovely Omega underneath him is gonna be the death of him. 

  
He didn't know how long his knot lasted but he was sure they didn't stop at only a round. His hut was filled of muffled moans and noises of sweaty bodies colliding. Good thing his hut was located outside of the village and everyone was fast asleep or else he wouldn't have the courage to face the villagers knowing that they might have heard Gen and his mess the whole fucking night. 

  
As to what happens next? Senku wasn't exactly sure but if there is one thing that he had confirmed in this accident... it was that he's 10 billion percent positively sure that he likes the mentalist. 

His alpha at least. 


End file.
